figure('Position', [0, 0, 900, 400]);
subplot(1, 3, 1);
[X, Y, Z] = sphere(50);
contour3(X, Y, Z, 'LineWidth', 2);
[X, Y] = meshgrid(-2:0.25:2);
Z = X.*exp(-X.^2-Y.^2);
subplot(1, 3, 2);
contour3(X, Y, Z, [-0.2 -0.1 0.1 0.2], ...
'ShowText', 'on', 'LineWidth', 2)
[X, Y, Z] = peaks;
subplot(1, 3, 3);
contour3(X, Y, Z, [2 2], 'LineWidth', 2);
